1. Field of the Invention
The present invention relates to a heat exchanger structure of an automatic transmission and, more specifically, to a heat exchanger structure of an automatic transmission which can stabilize a temperature of oil.
2. Description of the Background Art
A conventional heat exchanger structure of an automatic transmission is disclosed in, for example, Japanese Patent Laying-Open No. 11-264318 (a patent document 1).
Patent document 1 discloses a structure including two heat exchangers, in which a heat exchange path of oil is switched based on a temperature of oil.
Switching of a switching valve (thermo valve) in a conventional technique is controlled with a temperature of oil subject to heat exchange by a first heat exchanger. The oil actually flowing into a transmission, however, may be subject to heat exchange by a second heat exchanger. Therefore, control of switching of the valve based on a temperature of the oil flowing into the transmission may not be possible.
The conventional heat exchanger structure described above has a problem that a temperature of oil cannot be stabilized readily.